In this work, we describe the successful preparation of a series of cocrystals of the modified nucleobase 1-ethyluracil with different coformers in a 1:1 or 2:1 (nucleobase:coformer) ratio including urea (URE) or some compounds containing carboxylic and hydroxyl groups such as l-malic acid (MAL), l-tartaric acid (TAR), 2-hydroxybenzoic acid (SAL), 4-hydroxybenzoic acid (4HB), and 2,4-dihydroxybenzoic acid (DHB). The influence of the hydroxyl substituent on the alkyl chain for 1·TAR and 1·SAL cocrystals or the phenyl ring for 1·SAL, 1·4HB, and 1·DHB multicomponent solids was studied. All of the compounds were characterized by powder X-ray diffraction, FT-IR, and thermal methods. Moreover, for those whose single-crystal structures could be determined, computational studies were also performed to investigate the factors that may affect the cocrystal formation, the recurrent motifs, and the energies associated with the H-bonding interactions using DFT calculations and a combination of the quantum theory of atoms in molecules (QTAIM) and the noncovalent interaction index (NCIplot) computational tools.

中文翻译：

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1-乙基尿嘧啶，一种用于制备多组分形式的新支架：合成、表征和计算研究

在这项工作中，我们描述了以 1:1 或 2:1（核碱基：共形成物）比例包括尿素（URE）或一些含有羧基和羟基，例如l-苹果酸 (MAL)、l-酒石酸 (TAR)、2-羟基苯甲酸 (SAL)、4-羟基苯甲酸 (4HB) 和 2,4-二羟基苯甲酸 (DHB)。羟基取代基对1·TAR和1·SAL共晶的烷基链或1·SAL、1·4HB和1·DHB的苯环的影响研究了多组分固体。所有化合物均通过粉末 X 射线衍射、FT-IR 和热法表征。此外，对于那些可以确定单晶结构的人，还进行了计算研究，以研究可能影响共晶形成、循环基序以及使用 DFT 计算和组合的 H 键相互作用相关的能量的因素。分子中原子的量子理论 (QTAIM) 和非共价相互作用指数 (NCIplot) 计算工具。